940 auto transmission glitch

[960kg]

On four of my Volvo 700/900 the lock up was around 55 to 60mph

The relay fault give away is the high revs when it drops a gear for no reason. Also the red arrow light should come up when it drops?

Only one of my motors in this series had a faulty relay and it was expensive £40 from Volvo in 1996. It was just the silver single square shaped one.

As you can see a long time since i owned them but i did have 30yrs of Volvo`s so only trying to help?

Forgot to say the id plate on the box should say AW70L....AW71L.....for lockup.

[Laird Scooby]

That confirms the Volvo data sheet that shows it to be around 60mph give or take and also shows a bit of variation between models with different engines.

However, are you talking about lock-up or overdrive? The orange arrow shows you don't have overdrive selected and is only a tell-tale to advise you have another gear, his is not only overdrive but lock-up as well, it would be interesting to know if the orange arrow appears when it drops out of lock-up. If so then it's dropping out of overdrive, not just lock-up.

Some cars will go into lock-up even without overdrive, for example on my non-Volvo cars, i can have lock-up in second (or even first) above 30mph under the right conditions.

[stegreg]

Thanks for your perseverence on this issue, very much appreciated. Yes, am still going to continue with oil changing, as the cable and gasket are going to take a couple of weeks to arrive anyway.

in the meantime, I had a closer look at the throttle end of the kickdown cable this afternoon.
Now, the info I read suggests there should be 0.5 - 1.0mm slack gap on the cable, between the metal cablw clip and the shroud on the cable as it fixes to the throttle bracket....

i cant get a gap! its almost as if something has happened to the cable and "pulled" it down in to the box. see pic. you can see ive slackened the addjuster off the cable outer, by the "sag" in the inner cable as it leads to wards the throttle drum, so it is slack...but if i ease the inner cable up from the box, i cannot feel and freeplay.20171228_144606.jpg

[Laird Scooby]

That would tally with my suggestion the outer cable has been pulled out of the box - check that end and make sure the cable outer is pushed into the box properly, i belive it's a firm-ish sliding fit, has been on the ones i've come across anyway.

Also if you pull the inner cable away from the throttle mechanism, can you get a gap as specified? If so that would point to the same idea.

[960kg]

A Quote from a Brickboard question?.....it may help about the cable at the box end?.......The tighter the cable adjustment , the more 'sporty' the acceleration (delayed shifting)

The AW71L on our 93 945 shifts much harder and less consistently than on our 91 745. I just read the AW kickdown cable adjustment section of the 700/900 FAQ then looked at the cable on our 945. To check the cable I detached it from the throttle drum. It retracts smoothly and with fairly constant tension. The amount of retraction is limited by a litle ferrule crimped to the cable. Currently the cable is adjusted so the ferrule moves off the rubber cap on the cable sheath just as the throttle drum starts to turn.

With the cable detached from the throttle drum, I could not hear or feel the motion of the cam referenced in the FAQ: "Listen carefully, and you'll hear the cam that the cable is attached to in the automatic transmission click up against its stop"

If I cant hear the cam, is the cable not retracting far enough, even though it cant retract any further due to the ferrule ? Or is something not right in the transmission ?

Is it OK to loosen the cable so it doesnt start to move until after the throttle drum has rotated a few degrees ?


You need to pull the cable out one centimeter, about 1/2 and inch, and release it. It should slap back and you should hear and audible "clack" noise from down in the trans. If you do not one of two things is happening, 1 the cable is misadjusted and needs to be slackened or 2 someone has replaced the cable and when they installed the little metal piece on the cable itself they had the cable misadjusted and installed the metal piece too far up the cable so that the metal piece will not allow the cable to go far enough back into the sheath to allow the valve to slap shut inside the trans. If your car shifts too soon you have too much slack in the cable and if it shifts too late then your cable is adjusted too tight. If you cannot get enough slack into the cable because of an improperly installed metal piece then you need to carefully cut it off and install a new one properly.

[stegreg]

Me thinks the next thing to do is get underneath again. find the kickdown cable where it drops in to the box and have a good look, make sure its seated right.
"IF" it the cable has jumped out, then that would explain why it just suddenly happened, "but was ok before" type scenario..

I'll just pray for dry weather, unlike the snow covered frost we had overnight [again]. !!
Im off tomorrow [friday] , so lets see what we can see then, fingers crossed, but whilst im under there, will do another oil change, being as the oil dipstick coupling is being freindly and can unscrew to drain from there too now, rather than sucking up the dipstick tube.

[stegreg]

Right, after waiting a while for the nasty frost to clear, managed to crawl underneath to check the kickdown cable out. Unfortunately, yep, it looks secure in to the housing and hasnt jumped out any, not even a mm. So, then did another partial oil change. Er, YES there is a drain plug, but oddly it was an internal hex socket type, so was flush with the sump pan, so thats why it didnt appear earlier to have one, so drained the complete sump pan out, and replaced with fresh oil.
Its looking a little better, now it only looks a dark brown with reddish tint. LOL, rather than the black stuff i started with, so getting there slowly.
Not roadtested since this oil change yet, have to wait till Saturday. but heres pic of todays oil giggle.20171229_140826.jpg

[Laird Scooby]

I'm looking forward to the road test report now!

[stegreg]

Ok, so road test this morning, took it for a steady run up a motorway, get the speed over 50 so to speak.
One the run out....nothing to report, the box still behaving as originally, still wont lock in to overdrive, speed, 70mph, revs 3600rpm.

I did a short stop, and decided to try something. I totally disconnected the kickdown cable from the throttle drum.
then took back on to the motorway for 3 miles. Apart from the box changing so smoothly i barely noticed any change at all, but had to of done as the revs didnt say i was still in 1st !! LOL.

So cane off at next junction, dropped in to a layby, reconnected the kickdown cable. BUT this timw i pulled the yellow rubber protector off the end of the cable, as mine always seems to run firmly pushed up against it, thus now seeing a bit of "freeplay" in the cable. Yep, do appreciate the protector stops crap going down the inner, but for this trial....had to try something.

Again travelling at 70, 3600rpm, I backed off the throttle, and yes, 4th kicks in, and you see the revs drop by around 1200 rpm...BUT if you just touch the throttle to maintain speed, it slips right out again.

So tried another idea. at steady 70, with throttle lightly applied, if i click the 3rd lock switch on the stick..warning light on dash tells me its engaged AND revs now drop by id say 200 rpm.

SO, it seems the overdrive IS stil engaging, but for some reason its not locking fully, its loosing pressure or something somewhere.

YES, could still be some bits in the box, thats still yet to flush out and is holding a valve partially open, maybe even a bit of this in the overdrive solenoid?

Checked the poil level when back home too...level normal/hot ok...oil on cloth now just a reddy brown....so yes, the oil is clearing, but not ready for the cigar yet !.......but possibly hearing some singing far far away.

[960kg]

Thing is when you say it "slips out again on gentle throttle touch to maintain speed"..........this is what does happen as you are on the revs and speed at which it goes into Lock Up and not 4th gear?

You are slipping in and out of Lock Up.

If you travel above or below this critical speed then all should be correct it will not slip out or change up.

I do believe your operation is completely normal?

It is designed to do this otherwise how would it do it, change gear or lock up?....it has to happen somewhere in the rev range and or according to load.